Low-noise quick-start low-dropout linear regulator

Abstract

The invention provides a low-noise quick-start low-dropout linear regulator and belongs to the field of power management. The low-noise quick-start low-dropout linear regulator comprises a band-gap reference voltage source, a pre-adjustment module, a low-pass filter and an error amplifier, wherein the band-gap reference voltage source provides stable reference voltage for a pre-adjustment amplifier, the pre-adjustment module comprises the error amplifier and a resistive voltage-dividing network and is used for adjusting the band-gap reference voltage into voltage to be outputted, the low-pass filter is connected to filter out noise of a reference module and a feedback resistor, output voltage passing through the filter is inputted into the error amplifier, and output voltage not changing along with inputted power voltage and a load is provided according to a negative feedback principle. The low-noise quick-start low-dropout linear regulator has the advantages that the condition that a low-pass filter circuit has a low corner frequency can be guaranteed only with a small area, circuit start time cannot be affected, and the output voltage can be outputted with ultralow noise within a short start time, so that the chip area is greatly reduced and circuit noise performance is improved to a great extent.

Description

technical field [0001] The invention relates to the field of power management, in particular to a low-noise, fast-start low-dropout linear regulator. Background technique [0002] With the popularization of portable electronic products, the power management system is more and more important, and the quality of the power management part determines the performance of the whole system to a large extent. Compared with switching power supply DC-DC, low dropout linear regulator LDO (Low Dropout Linear Regulator) has extremely low output voltage noise, ripple and high power supply rejection ratio, which can meet the requirements of noise-sensitive RF circuits and analog circuits. The requirements for power supply voltage, and in some systems, the combination of switching power supply and LDO makes the advantages of both fully play, and provides customers with high-efficiency and low-noise power supply. [0003] In some high-performance systems, when a high-noise power supply is us...

AI Technical Summary

Problems solved by technology

For the above reasons, there are several commonly used solutions to reduce noise: (1) filter the inherent noise of the reference through a low-pass filter, but the low-pass filter implemented on-chip often requires large resistors and capacitors to achieve low Corner frequency, which will consume a large chip area and increase cost; (2) reduce the noise of the reference source, you can use the Vth reference source and Vbe reference source, they have good noise characteristics, but the output reference voltage accuracy is poor, with the process It has a great influence on temperature and power supply noise; (3) reducing the ratio of the feedback resistor R1 to R2, and reducing the resistance of R1 and R2 at the same time can reduce the thermal noise of the resistor

However, these methods will greatly increase the area and power consumption of the circuit, or make the LDO reference voltage source less accurate, resulting in low output accuracy and limited output voltage value.

To sum up, the traditional LDO structure cannot achieve very low noise performance, and a novel circuit structure must be used to improve performance

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